George R. R. Martin, whose “A Song of Ice and Fire” fantasy book series is the basis for the hit HBO show “Game of Thrones,” has released a chapter of his forthcoming book, “The Winds of Winter.”

The book, with a release date yet to be determined, will be the sixth installment in the series and is a long time coming after 2011’s “A Dance With Dragons.” Martin has said the series will contain a total of seven books, with the final installment — “A Dream of Spring” — also forthcoming with no definite release date in sight.

Martin released the chapter, titled “Mercy,” on his website, replacing a previously released excerpt titled “Arianne.” The new chapter, Martin wrote on his blog, “is actually an old chapter” that was written “a long time ago,” before previously released samples of the book, but had only been seen by his editors. Many would-be readers took to social media to complain of problems accessing the chapter after fervent fan interested crashed the site, which appears to be up and running again.

A warning to the uninitiated: Stop reading now if you want to avoid spoilers.

The new chapter centers on Arya Stark, a fan-favorite character who throughout the novels takes on alias after alias in her quest to seek vengeance for her family’s suffering. In the chapter, released on Martin’s website, Arya is posing as a mummer named Mercy in the port city Braavos, preparing for her first speaking role. Her troupe is set to perform before an envoy from Westeros, and Arya spots a familiar face among the guards — one whose name she has repeated nightly.

As HBO’s “Game of Thrones” marches into its fourth season, based primarily on events in the third book in the series, “A Storm of Swords,” many fans worry that the show will catch up to and surpass the events of the books. The sentiment was expressed on social media, with some “Song of Ice and Fire” fans taking their complaints to Twitter.

Is anyone else upset that another chapter of The Winds of Winter has been released? Just publish it all already… #tiredofwaiting

Meanwhile, the fourth season of “Game of Thrones” premieres April 6, bringing the world of Westeros back to the small screen after a 10-month hiatus.

Judging by the trailers, the season promises plenty of action and, of course, intrigue as the Lannister, Stark and Tyrell clans deal with the fallout of the so-called Red Wedding, which saw a host of main characters massacred. Cruel King Joffrey (Jack Gleeson) prepares to marry Margaery Tyrell (Natalie Dormer), Jon Snow (Kit Harington) prepares to defend the Wall against a Wildling invasion, and Daenerys Targaryen (Emilia Clarke) continues her conquest of Slaver’s Bay.

What do you think of the new chapter? Will you be tuning in for the “Game of Thrones” premiere? Let us know in the comments.